Drawing sheet glass



Dec. 7 1926. 1,609,999

E. T. FERNGREN DRAWING SHEET GLASS l Filed Sept. 10', 1923 3Sheets-Sheet 2 A7' TNE Y ,Patented Dec. 7, 1926. A Y

uNiTEo srATEs y 1,609,999- vPaTENT OFFICE.

ENocE T.,'EEENGEEN, OF TOLEDO', OH'IO, assioma fro THE LrEBEY-OWENSSHEET @Lass COMPANY, OF TOLEDO, OHIO, A CORPORATION or omo. v

DRAWING SHEET Grass.

` Application led' September 10, 1923. Serial No. 661,740.

This invention relates to improvements in the art of drawing sheetglass.- f. The ob-` jects of the invention are, more particularly, tofacilitate the flow of'molt'en glass to the sheet source, to lpreventvthe stagnation .and devit-rication of portions of this molten streamadjacent the sheet source, vand to simultaneously convert a portion ofthe molten stream into cullet, which subsequently may, be used in theproduction of molten glass.

vlin certain forms of sheet glass drawing apparatus previously used, forexample, the apparatus disclosed in the patent to Colburn 1,248,809,granted December 4, 1917, the molten glass from which the sheet is drawnis held in a shallow container or draw-pot which is closed at the sidesand one end, and in open communication at the opposite end withv a tankfurance or other source of molten glass. Since all of the molten glasswhich flows into this container to replenish the supply drawn away insheet form comes in at one-end of the container andv at one side of the"sheet source, there is a tendency for the glass at the other side of thesheet source, lin the closed end of the container, to become more orless stagnant, and sometimes. devitriiication takes place. Also, theglass at the sides of-the container adjacent the sources of the sheetedges is subject to greater cooling influences than `the remainder ofthe molten pool due to the proximity ofthe cooled sheet edge-formingin-` strumentalities positioned directly thereabove. There is conseuently a tendency for the molten glass adjacent these sheet edge sourcesto become unduly chilled and devitrilied. Duringthe drawing of the sheetthere is established a stream movement along' a certain defined-'pathwithin the body o glass in the pot, an the glass which moves in thispath continuously supplies the sheet formation, while the-,glass of thebody which 'g r lies on the outskirts of this path is very lslowly if atall includel in the stream movement. .It has been found that during aperiod'ot about three or four weeks a gradual change occurs in thenature and composition of this glass which is outside of the maincurrent towards the sheet, and that in this space of time there is beingbuilt up through eglassfrom the inner walls of the pot toward the limitof the stream path inthe body a formation of exceedingly tenacious vandin part devit'riied glass which grows to such an extent that itencroaches upon and obstructs the normal path for the glass movementtoward the sheet, making it difficult to obtain an even sheet, andcausing lines, cords and dogmetal defects in the sheet. To overcomethesediiiculties it becomes necessary to discontinue the drawing operationand boil out the pot,.an operation which involvesmuch time and labor,and an ,intensev application of- 'heat before normal conditions arerestored and thesheet drawing operation renewed.

According to theV present invention, the

container or conduit for the molten pool is 4 so modified as to providepassages for the overflow Or descending discharge of a certain portionof the molten glass from the container at the points most subject tostagnation, as noted above, so that there will be a 4continualreplacement of the molten glass at these positions and-the causes ofpossible devitrification will be eliminated. Thus in the presentinvention the sheetsupplying current inthe supply body of glass is in away assisted to arrlval at the point of sheet formation, by a carryingvehicular stream current including all the glass of the body which islocated beyond the limits of the direct sheet-supplying current, thusinsuring a constant unimpeded path for the' sheet-supplying glass,relieving the drawing Atension in said glass, and also making itpossible to maintain the glass of the entire supply body in a uniformsolutional state, and thereby avoidin the production 4of much defectivesheet g ass. Provisions are made to collectthe glass which overflows atthe several points from the container, and this molten glass isimmediately sub- 'ected to' a rapid chilling treatment whereby itisconverted into a v'friable granular cullet, which latter productisespecially desirable asa glass producing material.

Other objects and advantages of the invention will be apparent from thefollowing detailed description of certain approved forms of 'theapparatus. `In the 4accompanying drawin s:

Fig. 1 is a vertical longitu inal section through one form of theapparatus. Fig. 2 is a transverse vertical section taken vsubstantiallyon the line 2-2 of Fig. 1.-

Fig. 3 is a plan view of the apparatus shown in Fig. 1, the cover-tilesfor portions ico of the molten glass in the receptacle being omitted.

Fig. 4 is a partial vertical section taken substantially o n the line 44of Fig. 2.

Fig. 5 is an end elevation of a modified -the molten glass 1 flows intothe shallow conduit or container 2 from a tank furnace or other suitablesource of molten glass, the discharge end of which is indicated at 3.The adjoining open ends of receptacle 2 and tank 3 are of substantiallythe same depth so that a free and uninterrupted passage is permitted forthemolten glass 1 into the receptacle. The other end and the two' sidesof receptacle 2 are substantially closed so as to maintain a pool ofmolten glass within the receptacle, although suitable overflow passagesare provided as hereinafter described.

The glass sheet 4 is drawn upwardly from the surface vof the molten poolin receptacle 2 by any suitable drawing means, indicated generally at 5.Edge-forming rolls or other instrumentalities 6 engage the sheetedgesadjacent their source, to aid in drawing these edges from the moltenglass and in maintaining vthe width of the sheet. These edge-drawingrollers 6 are internally cooled and exert a certain chilling effect onthe glass in their vicinity.

Channels 7 are formed in theside walls 8 of receptacle 2. Each of thesechannels communicates with the pool 1 of molten glass somewhat below`the normal glass level,

and directly opposite thesource of the sheetv edge as at 9. Each channel7 slopes downwardly from the end 9. just described, toward the closedend of the receptacle so that the molten glass which overflows at 9 intothese side channels will flow out through the closed end of the pot asat 10. Spaced inwardly a short distance from the closed end 11 ofreceptacle 2 is a retaining wall 12, whose upper edge is slightly belowthe normal glass level, the bottom of the pot sloping up to meet thiswall 12 as at 13. Invthis way the pool or stream of glass 1 is madegradually shallower as it approaches the `overflow wall 12, so that thestream finally terminates in a shallow cascade of glass 14 which liscaught by the channel between walls 1l and 12 and flows therein towardeither side of the receptacle where these streams meet and join with theoverflow 10 from the side channels 7. The molten streams 10 are caughtin a trough member l5, whose glass-holding cavity slopes from either endtoward a central orifice 16 from which ythe glass flows down in stream17 into a chute 18 positioned beneath the machine. l

Chute 18 is supported near one end on a pivot 19 and its other end restson a rotary cam member 2O which imparts a continuous joltin'g or shakingmovement to the chute 18. Vater from one or more pipes 21 is directedupon the stream of molten glass flowing into chute 18, and the chillingeffect of this water, in combination with the jolting movement limpartedby cam 20, converts the molten glass into granular cullet which slidesdown the chute 18 into a suitable receiving member.

The surface glass yin receptacle 2 ateither side of the source of sheet4 is covered by the arched tiles 22 and 23, and the channels 7 in theside Walls of the receptacle are covered by tiles 24 in combination withthe tile 22, above described. The receptacle 2 is suitably supportedover a heating chamber 25 which keeps the molten glass within thereceptacle at the proper temperature. It will be noted that the trough15, which collects the overflowing molten glass, is located within thisheating chamber 25, also that of. the channels through which thisoverflowing glass passes are located within the heated atmosphereprovidedpby `this chamber so that the streams of glass in these passageswill -remain molten until it flows out into the chute 18. Passages 26between the coverltiles 24 and the side walls 8 of receptacle 2 willpermit a portion of. the heated atmosphere ,from chamber25 to flow outover channel 7 onto the surface vglass adjacent the sources of the sheetedges to counteract, to some extent, the cooling influence of edge rolls6 at these points.

A somewhat modified forml of receptacle is shown in Figs. 5 and 6. Inthis case the channel 27 between the outer wall 28 ot receptacle 29 andthe overflow wall S0, slopes towards its central portion, instead ofoutwardly as in the fornr previously described, so that the molten glasswhich overflows into this channel 27 flows out in a central stream, 31,and thence downwardly into chute 18. In this way the trough member 15previously described may be eliminated. It 'will be noted that in theform of receptacle shown in Figs. 5 and 6, the overflow .sages 34through which a portion of the lun lflfi molten stream l may flow out toprevent the accumulation of stagnant 'glass at the closed end of thereceptacle. Plunger or t stop members 85 project down, into or slightlyabove. these passages 34 to control the outward-flow of glass at thesepoints. The plungers mav be reciprocated at intervals lin any suitablemanner, or may be per manently positioned above the passages 34: .so asto permit a constant flow of desired volume through these passages.

It will be seen that with any of the forms ot' this improved apparatus,the flow of glass into the draw-pot or receptacle is continued beyondthe sheet source, and a constant replenishingl movement takes place atthe point-s which would be more Or less stagnant were it not for theoverflow passages provided. The sideward flow of glass throughchannels-9 also aids in maintainingr the width of the sheet source andconsequently" the width of sheet 4. The overflowing molten `glass whichis not drawn into the sheet is not a loss, as it is quite desirable toform a certain amount of granular cullet to be used as a portion of t-hebatch with which the tank furnace is replenished. It has been found thata batch containinpr a large percentage of this kind of cullet is mosteilicient for producing;r the qualitvY of molten glass best adapted fordrawing into sheet form.

Claims:

l. In a sheet glass drawing appa 'atus, a container for the molten glassfrom which the glass sheet is drawn, the container being in opencommunication at one end with a source of molten glass, and havingoverbeing of such a height as to permit a constant overflow of glassfrom the said drawpot, and means for drawing a sheet from the glass inthe draw-pot.

3. In sheet glass apparatus, a tank furnace containing a mass of moltenglass, a drawpot in open communication therewith, the wall at the closedend of the draw-pot having a shape lto permit a constant overflow of.waste glass, and means to draw a sheet from the glass in the draw-pot,the overiow of waste glass preventing stagnation of unused glass in thedraw-pot.

4f. In sheet glass apparatus, a tank furnace containing a mass of moltenglass, a draw-pot in open communication therewith, means. to draw asheet therefrom, means to permit an overflow of glass from the pot atthe ends of the sheet being formed, and means to permit an overow at theclosed end of the pot.

In sheet glass drawing apparatus, a tank furnace containing a mass ofmolten glass, a draw-pot in open communication therewith, means fordrawing a sheet therefrom, means arranged at the edges of the sheet forholding the same to width, and means to permit an overflow of the glassdirectly beneath the said width means to prevent an accumulation ofchilled glass.

Y6. In sheet glass drawing apparatus. a tank furnace containing a massof molten pdass, a drawpot in' open communication therewith, means fordrawing a sheet there.-

from, means arranged at the edges of'tlie sheet for holding the same towidth, andl means to permit an overflow of the glass directly beneaththe said width means to .prevent an accumulation ot' chilled glass, andthe end of the container having means to permit a constant overflow ofthe glass not. drawn into the sheet.

Signed at Toledo. in the count;7 of Lucas and State of Ohio, this 6thday of September, '1923.

ENOCI-I T. FERNGREN.

